


























































































































































































































































THE U.S. ARMY CAMPAIGNS of the MEXICAN WAR 





















£r*/C*s" 

UBRAMY of CONSNCMI ; / 




Introduction 



i 


The Mexican War (1846-1848) was the U.S. Army’s first experience 
waging an extended conflict in a foreign land. This brief war is often 
overlooked by casual students of history since it occurred so close to the 
American Civil War and is overshadowed by the latter’s sheer size and 
scope. Yet, the Mexican War was instrumental in shaping the geographical 
boundaries of the United States. At the conclusion of this conflict, the U.S. 
had added some one million square miles of territory, including what today 
are the states of Texas, Arizona, New Mexico, and California, as well as 
portions of Colorado, Wyoming, Utah, and Nevada. This newly acquired 
land also became a battleground between advocates for the expansion of 
slavery and those who fought to prevent its spread. These sectional and 
political differences ripped the fabric of the union of states and eventually 
contributed to the start of the American Civil War, just thirteen years later. 
In addition, the Mexican War was a proving ground for a generation of U.S. 
Army leaders who as junior officers in Mexico learned the trade of war and 
latter applied those lessons to the Civil War. 

The Mexican War lasted some twenty-six months from its first 
engagement through the withdrawal of American troops. Fighting took place 
over thousands of miles, from northern Mexico to Mexico City, and across 
New Mexico and California. During the conflict, the U.S. Army won a series 
of decisive conventional battles, all of which highlighted the value of U.S. 
Military Academy graduates who time and again paved the way for American 
victories. The Mexican War still has much to teach us about projecting force, 
conducting operations in hostile territory with a small force that is dwarfed 
by the local population, urban combat, the difficulties of occupation, and the 
courage and perseverance of individual soldiers. The following essay is one 
of eight planned in this series to provide an accessible and readable account 
of the U.S. Army’s role and achievements in the conflict. 

This brochure was prepared in the U.S. Army Center of Military History 
by Stephen A. Carney. I hope that this absorbing account, with its list of 
further readings, will stimulate further study and reflection. A complete list 
of the Center of Military History’s available works is included on the Center’s 
online catalog: http://www.army.mil/cmh-pg/catalog/Brochure.htm. 


LC Control Number 



|| III II li ii n '■ 11 

2006 372175 


j 


JOHN S. BROWN 
Chief of Military History 

















The Occupation of Mexico 
May 1846-July 1848 


The Mexican War altered the United States and its history. During 
eighteen months of fighting, the U.S. Army won a series of decisive 
battles, captured nearly half of Mexico’s territory, and nearly doubled 
the territories of the United States. Initially, three U.S. Army forces, 
operating independently, accomplished remarkable feats during the 
conflict. One force—under Brig. Gen. Zachary Taylor—repelled initial 
Mexican attacks at Palo Alto and Resaca de la Palma, north of the Rio 
Grande. Subsequently, Taylor’s force crossed the river and advanced into 
northern Mexico, successfully assaulted the fortified town of Monterrey, 
and—although heavily outnumbered—defeated Mexico’s Army of the 
North at Buena Vista. 

Concurrently, Col. (later Brig. Gen.) Stephen W. Kearny led a 
hardened force of dragoons on an epic march of some 1,000 miles 
from Fort Leavenworth, Kansas, across mountains and deserts to the 
California coast. Along the way, Kearny captured Santa Fe in what is 
now New Mexico and, with the help of the U.S. Navy and rebellious 
American immigrants, secured major portions of California. 

Maj. Gen. Winfield Scott directed the third and decisive campaign 
of the war. Scott’s army made a successful amphibious landing from 
the Gulf of Mexico at the port of Veracruz, which was captured after 
a twenty-day siege. Scott then led his army into the interior of Mexico 
with victories at Cerro Gordo, Contreras, Churubusco, Molino del Rey, 
and Chapultepec, ending the campaign and ultimately the war with the 
seizure of Mexico City. 

The conflict added approximately one million square miles of 
land to the United States, including the important deep-water ports of 
coastal California, and it gave the Regular Army invaluable experience 
in conventional operations. Yet, the Mexican War consisted of more 
than a series of conventional engagements, and no formal armistice was 
reached until long after the capture of Mexico City. Rather, the Army 
had to conduct a “rolling occupation,” thereby serving as administrators 
over the captured territory as the Army’s frontline units continued to 
pursue conventional Mexican forces. 

Incidentally, by definition, “Territory is considered occupied when it 



is actually placed under the authority of the. hostile army. The occupation 
extends only to the territory where authority Has been established 
and can be exercised” (as defined fn U.S. Army Field Manual 27-10 and 







based on Article 42 of the Hague Convention of 1907). Thus, the Army 
found itself facing the more difficult mission of occupying a foreign 
country with a small force while battling capable and highly motivated 
guerrillas. 

The U.S. Army designated small bodies of armed Mexicans who 
fought an irregular war against the Americans as “guerrillas.” Guerrilla , 
a term based on the Spanish word for small war, was initially used during 
Napoleon’s Peninsula War, 1808-14, to describe Spanish irregulars 
fighting the French. Army commanders also used the Mexican term 
rancheros to describe guerrillas. In the current study, the terms guerrillas 
and irregulars are used interchangeably. 

Both the occupation and the insurgency reflected existing 
sociopolitical realities of Mexico. Indeed, the country’s deep and often 
violent racial, ethnic, and social divisions further complicated the task of 
the occupying forces. Regional variations between northern and central 
Mexico, differences between the composition of Zachary Taylor and 
Winfield Scott’s armies and the threats they faced, and—not least—the 
great difference in policies pursued by the two commanders meant that 
the U.S. Army conducted not one but two very different occupations in 
Mexico during 1846^48. 


Strategic Setting 

Numerous factors affect the nature and structure of occupation as 
a military mission. The strategic and long-term goals of any occupier 
will shape the occupation policy. This policy should work toward an 
anticipated end state, which can run the spectrum from annexation to 
the restoration of independence. 

An occupying force faces several essential duties and the possibility 
of collateral missions. Primary responsibilities include enforcing the 
terms of the instrument ending conventional hostilities, protecting 
occupation forces, and providing law and order for the local population. 
Collateral missions may include external defense, humanitarian relief 
and—in some cases—nation-building, which can be the creation of an 
entirely new political and economic framework. Economic conditions, 
demographics, culture, and political developments all come into play 
and affect occupation policy. 

Mexico s Political and Social Situation at the Onset of Hostilities 

Race and ethnicity greatly affected the history and development 
of Mexico. The descendants of native American Indians, who had 


4 






inhabited the region before the arrival of the Spanish in 1519, greatly 
outnumbered those of European ancestry. Even before Mexico achieved 
its independence in 1821, Spaniards and the criollos , or Mexican-born 
Spaniards, made up only 20 percent of Mexico’s population but controlled 
the country’s government and economy. The remainder comprised 
Indians and mestizos , the latter group being of mixed European and 
Indian heritage. Criollo control continued after independence. 

Although the Mexican population was divided along cultural, 
economic, and racial lines, the criollos themselves were split between 
conservative and liberal factions. Conservatives advocated installing 
a strong centralized government, having Catholicism as the official 
state religion, and limiting voting rights to the privileged few. Liberals 
proposed granting additional powers to Mexico’s states, defended 
religious toleration, and supported the expansion of voting rights. To 
complicate the political scene, the liberals further subdivided themselves 
into purist and moderate factions, each with different agendas. As a 
result, the government in Mexico City remained in a seemingly constant 
state of disarray that contributed to economic stagnation and an ever¬ 
growing national debt. 

At the onset of the conflict with the United States, the Mexican 
government was, in theory, a representative democracy. The Constitution 
of 1824 had created a federal system modeled on the U.S. Constitution. 
The Mexican federal government was composed of three branches: 
an executive branch with a president and vice president; a legislative 
branch, or general congress, comprising two houses—a senate and 
house of representatives; and a judicial branch with a supreme court 
and local circuit courts. 

In theory, the executive and legislative officials were elected 
through popular vote, but, in reality, only a small fraction of Mexico’s 
population actually had the right to vote. In 1846, for example, less than 
1 percent of Mexico City’s population of some 200,000 met the property 
requirement necessary to vote. Even smaller portions of the population 
in outlying regions were able to vote. The ruling elite refused to extend 
suffrage to the remainder of the population and cautiously guarded 
its power and land holdings, which further alienated the Indians and 
mestizos. As a result, rebellions were common in Mexico. In 1844, 
for example, a revolt against the central government led by Gen. Juan 
Alvarez soon turned into an Indian insurrection that spread a swath of 
destruction across 60,000 square miles of southwestern Mexico centered 
on Acapulco. Although the Mexican Army mercilessly repressed such 
outbreaks, underlying tensions seethed close to the surface as the war 
flared along the Rio Grande in May 1846. 


5 

















Mexico itself comprised more than twenty 
separate states, although that number fluctuated 
over time. State and local governments were 
organized in the same manner as the federal 
government. In fact, the criollos dominated 
Mexico at the state (provincial) and territorial 
level just as they did in the national capital. 
The provincial governments paid homage to the 
federal authority in Mexico City, but political 
instability and the distance between the capital 
and many of the states enabled the provincial 
governments to enjoy a wide degree of autonomy. 
As a result, U.S. forces conducted much of their 
negotiations with state and local governments 
early in the war and had no real opportunity to deal 
with the central government until Scott launched 
his campaign against Mexico City. In sum, the 
country’s governing bodies were unprepared to 
deal with either internal or external crises. 

American Objectives 

In 1845, Mexico’s borders included more than 
one-third of the North American continent, with 
a population of slightly more than seven million 
people. North of the Rio Grande, Mexico’s 
holdings extended from the western borders of 
Texas and the Arkansas River in the east to the 
Pacific Ocean in the west (Map 1). The holdings 
included more than one million square miles 
of land in what today are the states of Arizona, 
California, Colorado, Nevada, New Mexico, 
Utah, and Wyoming. The geography of this 
sparsely populated territory included portions of 
the jagged Rocky Mountains and Sierra Nevada, 
the craggy Intermountain region, and the rugged 
Coast Range. In addition, stretches of largely 
uninhabited desert contrasted with potentially 
valuable agricultural assets such as California’s 
Central Valley. 

Those territories attracted the intense 
interest of many Americans, including President 


7 









President James K. Polk (Library of Congress) 


James K. Polk and his administration, which had several clearly defined 
goals at the onset of the Mexican War. Polk wanted to settle the disputed 
southern boundary between Texas and Mexico. Ever since winning 
independence from Mexico in 1836, the Republic of Texas had insisted 
that the Rio Grande constituted the border separating it from Mexico. 
Mexico, however, set the line some 150 miles north at the highlands 
between the Nueces River and the Rio Grande. When the United 
States accepted Texas’s application for statehood in December 1845, it 
inherited the Texan claim. 

The United States also coveted Mexico’s lands north of the Rio 
Grande to support its rapidly growing population of approximately 
eleven million by 1840. Looking westward to expand, the nation justified 


8 






its demand for land with the concept of Manifest Destiny, a belief that 
God willed it to control the entire North American land mass. More 
than the perceived will of God, however, was involved. Economics also 
played a central role in the concept. American explorers in California 
had reported deep-water ports along the west coast, valuable departure 
points when the United States sought to open trade between its own 
growing industries and lucrative markets in Asia. In an attempt to settle 
Texas border questions and to secure California, the U.S. government 
had offered several times between 1842 and 1845 to purchase both 
regions from Mexico. Mexico City refused all overtures because 
Mexican popular opinion insisted that the government preserve all of 
the territory that the nation had wrested from Spain. 

When the war officially began on 8 May 1846, President Polk had 
a clear set of objectives for the U.S. Army. Secretary of War William L. 
Marcy, writing for the president, ordered General Taylor’s force of some 
4,000 Regulars—or just under half of the entire U.S. Army—to seize as 
much territory in northeastern Mexico as possible. Meanwhile, Marcy 
sent Kearny’s force through New Mexico and into California with 
instructions to cut those regions off from the central government in far- 
off Mexico City. Polk and Marcy believed that the Mexican government 
would not resist an offer to purchase the territory if U.S. military forces 
already controlled it. 

US. Army Organization 

Organized along European lines, the standing U.S. Army, designated 
the Regular Army, contained specialized corps of infantry, cavalry, 
artillery, and engineers. At the outbreak of the conflict, it numbered only 
7,365 soldiers. In compliance with its missions of guarding the frontier 
and defending the nation’s coastline, the Army had scattered its units in 
small posts manned by units of company size or less across the eastern 
seaboard and through the interior frontier. Because entire regiments 
rarely assembled, the force seldom practiced large-unit tactics. 

The core of the Army consisted of its eight infantry regiments, which 
consisted of ten companies each. On paper, each company possessed 
fifty-five men, but at the onset of the war most averaged only thirty- 
five. Brigades consisted of an ad hoc collection of multiple regiments, 
and divisions contained several brigades. Those larger formations were 
temporary wartime organizations. 

Infantrymen in the American Army enlisted for five years and 
received an average pay of $7 per month. Offering low wages and harsh 
discipline, the service attracted the poorly educated and those with few 
opportunities in civilian life. In 1845, 42 percent of the Army consisted 


9 





of foreign nationals; 50 percent were Irish and the rest were from other 
European nations. 

The cavalry of the U. S. Regular Army consisted of two light regiments 
trained and designated as dragoons, both organized into five squadrons 
of two companies each. Trained to fight mounted or dismounted, 
dragoons were always scarce and difficult to expand in a timely fashion. 
Their training and equipment were deemed too expensive in terms of 
time and money to justify increasing the numbers. The Army’s lack of 
such highly mobile troops was evident throughout the conflict. 

The Army’s artillery arm was more robust. It contained a mixture of 
6-pound field artillery, as well as 12-, 18-, and 24-pound coastal defense 
weapons. Howitzers firing shells of 12-, 24-, and 32-pound weight added 
to the Army’s arsenal. In Mexico, the Army would use primarily light 
artillery against guerrilla forces. At full strength, American light field 
artillery companies had three two-gun sections and came with a large 
number of horses to transport the guns, ammunition, and most of their 
crew. Some “flying” companies had all of their troops mounted. 

The U.S. Army also fielded a small number of highly trained 
engineers who served in either the Corps of Engineers or the Corps 
of Topographical Engineers. Members of the former specialized in 
bridge and fortification construction. The latter created maps, surveyed 
battlefield terrain, and built civil engineering projects such as roads and 
canals. 

Soldiers from the Ordnance, Subsistence, and Quartermaster 
Departments provided logistical support. The Ordnance Department 
supplied firearms and ammunition, while the Subsistence Department 
secured bulk food items, such as barrels of flour, salt pork, and cured 
beef. Both operated in the rear along the Army’s lines of communication. 
The Quartermasters had the greatest responsibility. They supplied 
troops with all equipment other than weapons, such as uniforms, horses, 
saddles, and tents; they also arranged transportation and oversaw 
construction projects; and, during the Mexican War, they created and 
ran a series of advanced supply depots close to field operating forces 
that ensured a steady flow of provisions and equipment to the troops. 
Although its long supply trains and depots sometimes became targets 
for Mexican irregulars and bandits, the Quartermaster Department 
provided the Army with one of the most advanced logistical support 
operations in the world. 

In times of emergency, the United States called for volunteers to enlist 
in state-raised regiments to augment its small professional force. The use 
of volunteers was first established in the 1792 Militia Act. Volunteers 
were compelled to serve wherever the War Department required them. 


10 


State militia, however, could not be forced to travel beyond their home 
state’s borders. The practice stemmed from the country’s colonial history 
and its ideological aversion to standing armies as a threat to republican 
liberties, a prejudice bequeathed by European colonists and the 
Revolutionary War generation. When necessary, Congress gave the War 
Department permission to request a specific number of regiments from 
each state. State governors then issued calls for volunteers and named a 
time and place for the volunteers to gather. Once raised, the men were 
organized into companies, battalions, and regiments. Regiments elected 
their own officers, although governors sometimes selected field and 
staff grade officers. The president appointed all volunteer generals, who 
were then confirmed by Congress. After the regiments were organized, 
they “mustered” into federal service and came under War Department’s 
control. They were not, however, governed by the 1806 Articles of War, 
the basis for the American military justice system, a situation that gave 
them much more autonomy than the Regular Army enjoyed. During the 
Mexican War, some 73,260 volunteers enlisted, although fewer than 
30,000 actually served in Mexico. 

The U.S. forces’ reliance on volunteer soldiers complicated matters. 
Because volunteers were taken directly from civilian life and quickly 
thrown into a rigid hierarchal system, many responded poorly to the 
regimentation of military life. At their worst, they resented superiors, 
disobeyed orders, balked against the undemocratic nature of military 
life, and proved difficult to control. They rarely understood and generally 
ignored basic camp sanitation, and they were generally unaccustomed 
to the harsh life faced by soldiers in the field. Not surprisingly, they 
experienced much higher death rates from disease and exposure than 
the Regulars. The officers of those regiments often held their rank 
by virtue of political appointment or through election by those who 
became their subordinates. This system offered no assurance that those 
who initially commanded possessed the ability or the training to lead. 
One senior Army officer concluded: “The whole volunteer system 
is wholly indebted for all its reputation to the regular army without 
which the [illegible] body of volunteers in Mexico would have been 
an undisciplined mob, incapable of acting in concert, while they would 
have incensed the people of Mexico by their depredations upon persons 
of property.” 

Swept by “war fever,” the men who initially rushed to join Taylor’s 
army in northern Mexico exemplified the worst characteristics of the 
lot. As a group, the early volunteers were vehement racists, vocal 
exponents of Manifest Destiny, and eager to fight and kill Mexicans— 
any Mexicans. They had little patience with the hardships of camp 


11 







life, strict codes of discipline, hot Mexican sun, prohibitive rations, 
or boredom of garrison duty. Drunkenness flourished because alcohol 
provided an easy escape for men who found the normal day-to-day 
routine of soldiering far removed from their dreams of adventure and 
military glory. Brawls fueled by gambling, regional rivalries, and general 
boredom were common. Violent confrontations between the ill-trained 
American soldiers and Mexicans were also frequent. 

Volunteers who arrived later in the war knew better what to expect 
and proved less unruly. In addition, commanders gradually found ways 
to control and occupy their new soldiers, which lessened their onerous 
effect on the Mexican citizenry. During the final months of the conflict, 
most of the volunteer troops conducted themselves with greater self- 
restraint in camp and proved quite effective on the battlefield. 

Throughout the war, both Taylor and Scott also relied heavily on 
special companies of mounted volunteers: the Texas Rangers, who acted 
as the eyes and ears of the Army by conducting crucial reconnaissance, 
collecting intelligence, and carrying messages through Mexican lines. 
They also launched raids against specific targets, especially guerrilla 
encampments. Technically state militia and not mustered into federal 
service, the Texans voluntarily agreed to serve in Mexico. Their 
depredations on the Mexican citizenry were often excessive, however, 
and their behavior, along with that of other volunteers, did much to 
spark local Mexican resistance. 

U.S. Army Counterinsurgency Doctrine 

The U.S. Army had no official doctrine covering occupation or 
counterinsurgency operations in 1846. In the absence of formalized 
manuals, its professional soldiers instead passed on informal doctrine 
that was based on traditions and experiences from one generation of 
officers to the next through personal writings and conversations. Little 
of it applied directly to the situation the troops encountered during the 
Mexican War. For example, American forces had no experience in the 
control of foreign territory other than a winter’s occupation of portions 
of Quebec Province during the American Revolution and some brief 
forays into Canada during the War of 1812. In 1813 during a three-day 
sojourn in York, the Canadian capital, American troops had looted and 
then set fire to large portions of the town and its harbor. This unhappy 
precedent, the product of poor discipline and heavy losses, possessed 
more relevance in 1846 than some American commanders chose to 
acknowledge. 

The volunteers’ actions during the various Indian Wars also 
bequeathed a mixed heritage. The Second Seminole War (1835-42), 


12 



I 

which pitted the Army against some 1,500 Seminole and African- 
American warriors in the Florida Everglades provided a particularly 
relevant example. The Seminoles used their knowledge of the nearly 
impenetrable Florida swamps to conduct ambushes whenever possible. 
In response, the Army shunned conventional tactics, such as trying to 
coordinate several converging columns over virtually impassible terrain, 
and adopted an unconventional approach. Commanders established a 
series of heavily garrisoned posts to protect white settlements and to 
limit the Seminoles’ ability to move with impunity. They also began 
active patrolling from those posts to find and destroy Indian villages and 
crops, as well as Indian war parties whenever possible. The tactics were 
both brutal and effective. Generals Taylor and Scott would apply similar 
measures during the occupation of Mexico. 


13 
















Mexico s Guerrilla Tradition and Composition 

of Irregular Forces 

In 1846, most Americans knew little about Mexican society, culture, 
or history. They did not realize that guerrilla warfare formed a central 
part of Mexico’s military tradition throughout the nineteenth century. 
During Mexico’s War for Independence, the poorly equipped rebels 
often resorted to hit-and-run tactics by mounting small-unit attacks on 
Spanish military detachments and the long supply trains that equipped 
them. 

Expert horsemen, Mexican guerrillas usually fought while mounted. 
Heavily armed with rifles, pistols, lances, sabers, and daggers, they 
showed particular skill with lassos and preferred to rope their victims 
and drag them to death when possible. They mastered the local terrain 
and had the ability to use complex networks of paths, trails, and 
roads to strike the unwary and then to disappear into the countryside. 
Fortunately for the Americans, many guerrillas doubled as thieves who 
failed to differentiate among their victims and often attacked their 
own countrymen for personal gain. Although the general population 
sometimes supported them, many Mexicans tired of their attacks and 
occasionally worked with the Americans to stop them. 

The Mexicans also employed irregular cavalry units, often raised 
from local ranchers and commanded by regular troops. In modern 
military terms, those forces would be designated as partisan fighters. 
“Partisan” describes organized guerrilla bands fighting under Mexican 
regular officers or officially sanctioned by the Mexican government. 
The term “partisan” did not enter the U.S. Army lexicon until 1863 in 
General Order No. 100, which differentiated between armed prowlers, 
guerrillas, and partisans. The term is appropriate in the current study, 
however, because there was considerable partisan activity during the 
conflict, especially in central Mexico. 

Although not officially part of the Mexican Army, the partisan 
cavalry often operated under close supervision of the regular army. 
Although Generals Antonio Canales and Jose Urrea were the best- 
known partisan leaders in northern Mexico, the Mexican government 
devoted considerable attention to raising partisan forces to harass the 
U.S. Army on its march toward the capital. Aware that Scott’s long 
supply line and the attitude of the civilians along this route were key 
to the success or failure of the American campaign, the leadership in 
Mexico City decided to disrupt convoys carrying ammunition and other 
supplies and to otherwise harass American forces. On 28 April 1847, 
just ten days after the Mexican defeat at Cerro Gordo, a newly installed 


14 



Mexican guerrilla (Coleccion Banco Nacional de Mexico) 

president of Mexico and adviser to Antonio Lopez de Santa Anna— 
the enigmatic Mexican strongman—Pedro Maria Anaya, ordered the 
creation of a series of volunteer Light Corps to attack Scott’s line of 
communications. Seventy-two Mexicans, most wealthy and twenty-one 
of them military officers on active service, received permission to raise 
the units. Brig. Gen. Jose Mariano Salas, a close friend of Santa Anna, 
played a prominent role in the effort. Terming the units “Guerrillas of 
Vengeance,” Salas recruited volunteers by vowing that he would “attack 
and destroy the invaders in every manner imaginable,” under the slogan 
“war without pity, unto death.” 

The units in the corps were designed to target supply and 
replacement convoys, small parties of American troops, and stragglers. 

15 








They used a variety of tactics. The larger forces operated as cavalry 
units, which sought to engage quickly, to inflict maximum casualties, 
and then to disappear rapidly. The smaller units made extensive use of 
sharpshooters who concealed themselves in the trees and chaparral that 
lined the Mexican National Highway, which Scott’s forces would use 
extensively. Imposing terrain features along most of the route’s length 
worked to the advantage of the partisans. 

Operations 

Because of Mexico’s immense size and population, the U.S. Army 
in reality occupied only a small area that encompassed key population 
centers along Mexico’s lines of communication. This arrangement was 
necessitated by the fact that the U.S. Army never maintained more than 
30,000 troops in Mexico during the entire war. The Polk administration 
expected this handful of soldiers—less than 0.4 percent of the total 
population of Mexico—to pacify some 7 million Mexicans. During 
the Mexican War, the United States occupied two regions of Mexico 
proper. Taylor and Scott occupied more than a thousand square miles 
of northern and central Mexico, respectively. Brig. Gen. Stephen W. 
Kearny’s troops did occupy a third area north of the Rio Grande—what 
today is New Mexico and California—but large numbers of Americans 
had already filtered into those regions and the United States did not 
intend to return either one to Mexican control. In addition, the areas of 
Mexico occupied by Kearny’s troops contained only 90,465 inhabitants 
as of the 1842 census. Of those, a significant number were U.S. settlers. 
Such a small number of civilians possessed far less potential for 
troubling a U.S force than did the millions of their countrymen who lived 
to the south. In addition, the area was already closely tied to the United 
States economically through well-established trade routes. The situation 
in those areas, therefore, was markedly dissimilar to what confronted 
Taylor and Scott in Mexico proper, which had little indigenous support 
for annexation. Because there were no significant guerrilla actions 
against Kearny, and he quickly integrated New Mexico and California 
into the United States, this study will not explore his occupation. 

Unique circumstances and personalities produced wildly different 
types of occupation in Mexico. Zachary Taylor, known to his troops as 
“Old Rough and Ready” for his casual demeanor and willingness to 
share his soldiers’ hardships, often neglected troop discipline. Winfield 
Scott, nicknamed “Old Fuss and Feathers” for his attention to detail and 
fondness for pompous uniforms, insisted on strict adherence to rules 
and regulations. 


16 






Taylor’s Occupation of Northern Mexico 

Zachary Taylor’s occupation of northern Mexico began on 12 May 
1846 when his troops crossed the Rio Grande and took the town of 
Matamoros unopposed. As the war progressed, Taylor extended his 
holdings. First, he gained control of Camargo, some eighty miles 
upstream from Matamoros, and then he went southward to Monterrey 
and eventually to Saltillo, approximately 140 miles southwest of 
Camargo (Map 2). The Saltillo to Camargo line became one of the most 
important supply and communications routes in the north. By war’s end, 
Taylor’s forces controlled a region extending as far as Victoria to the 
southeast and Parras to the west. 

Taylor quickly achieved the purely military objectives that the Polk 
administration assigned him. Within four months, he won decisive 
battles at Palo Alto, Resaca de la Palma, and Monterrey, thereby forcing 
Mexico’s Army of the North to withdraw some 400 miles south from 
the Rio Grande to San Luis Potosi. Taylor’s occupation of northern 
Mexico, however, did not compel Mexico’s government to sell any of 
the territories sought by the United States as President Polk had hoped. 
In fact, the situation in northern Mexico deteriorated rapidly in response 
to the local depredations of the volunteer troops. 

Until June 1846, Taylor’s army consisted of Regular Army troops who 
enjoyed some popularity with the citizenry. Matamoros’s citizens held the 
American force in higher esteem than they did the Mexican Army, which 
had abandoned all of its wounded when it retreated from the town. The 
U.S. Army had immediately set up hospitals to minister to the sick and 
wounded and had provided for the basic needs of the townspeople. 

The dynamic changed when volunteers moved into the area and 
immediately began raiding the local farms. As the boredom of garrison 
duty began to set in, plundering, personal assaults, rape, and other 
crimes against Mexicans quickly multiplied. During the first month 
after the volunteers arrived, some twenty murders occurred. 

Initially, Taylor seemed uninterested in devising diversions to 
occupy his men and failed to stop the attacks. As thefts, assaults, rapes, 
murders, and other crimes perpetrated by the volunteers mounted 
and Taylor failed to discipline his men, ordinary Mexican citizens 
began to have serious reservations about the American invasion. 
Taylor’s lackadaisical approach to discipline produced an effect utterly 
unanticipated by the Polk administration, many of whose members, 
particularly pro-expansionists such as Secretary of the Treasury Robert 
J. Walker, believed that Mexicans would welcome the Americans 
as liberators. Instead, public opinion turned against the Americans 


17 



and began to create a climate for guerrilla bands to form in the area. 
Mexicans from all social backgrounds took up arms. Some of them 
were trained soldiers; others were average citizens bent upon retaliating 
against the Americans because of attacks against family members or 


18 











Zachary Taylor (Library of Congress) 


friends. Criminals joined in, and bandits and highwaymen began to 
flourish, looking for easy prey. 

As Taylor’s force moved up the Rio Grande and its lines of 
communications extended, irregulars began to capture and kill 
stragglers, the sick, and the wounded who fell behind on long marches. 
The local populace increasingly appeared more than willing to support 
and shield the guerrillas. The volunteers’ racism, anti-Catholicism, 
and violence provided all the motive that locals needed to oppose the 


19 




American advance. Guerrilla attacks grew more frequent after the battle 
for Monterrey, when Brig. Gen. William J. Worth, the new military 
governor of the city, discontinued military patrols in the town for a short 
time, allowing a bloodletting to occur. 

Taylor appointed officers to serve as military governors of all major 
towns that he occupied. Each military governor had authority to make 
whatever rules he wished. There was no official military governing 
policy at the time. Observers estimated that volunteer troops killed 
some 100 civilians, including many who had been killed by Col. John 
C. Hays’ 1st Texas Mounted Volunteers. A few weeks later, apparently 
in retaliation, Mexicans killed a lone soldier from a Texas regiment 
just outside Monterrey. Rangers under Capt. Mabry B. “Mustang” 
Gray responded by killing some twenty-four unarmed Mexican men. 
The event galvanized much of the population against Taylor’s Army of 
Occupation. 

The boredom of occupation duty led to additional waves of 
violence. During November 1846, for example, a detachment from the 
1 st Kentucky regiment shot a young Mexican boy, apparently for sport, 
and Taylor again failed to bring any of the guilty soldiers to justice. 

The most concerted and organized irregular campaign in northern 
Mexico began in February 1847, during the initial phase of the battle 
for Buena Vista, and it lasted nearly a month. As Taylor repositioned 
his troops around Saltillo to contest Santa Anna’s advance, the Mexican 
commander sent a detachment of partisan cavalry under General Urrea 
to sever the Monterrey-Camargo road, Taylor’s line of communication 
to the Gulf coast. Urrea’s cavalry joined forces with General Canales’ 
force of partisan irregulars, which had been active in the region since 
the onset of hostilities the previous spring. Urrea was determined to 
strike isolated garrisons and Taylor’s lightly defended supply trains. 
As Taylor’s lines of communications had lengthened and become more 
difficult to defend, his supply convoys had become attractive targets for 
guerrillas, a vulnerability that he failed to recognize. 

On 22 February, Urrea’s mounted guerrillas attacked a wagon train 
containing some 110 wagons and 300 pack mules just five miles outside 
the undefended hamlet of Ramos, which was some seventy-five miles 
northeast of Monterrey. While a portion of the attackers surrounded the 
train’s guards posted at the front of the column, others went directly 
for the wagoneers. During the short skirmish, Urrea’s men killed 
approximately fifty teamsters, drove off the survivors, forced the guards 
to surrender, and captured most of the supplies. 

The partisan commander next gathered up the undamaged wagons 
and mules and moved on to attack the American garrison at Marin, 


20 


arriving late that evening. Two companies from the 2d Ohio under the 
command of Lt. Col. William Irvin—some 100 men—defended the 
town. They held the irregular cavalry at bay until 25 February when 
a small relief column finally arrived. Low on supplies, the troops 
abandoned Marin and moved back toward Monterrey. Unknown to Irvin 
and his rescuers, the rest of the 2d Ohio, commanded by Col. George W. 
Morgan, was marching south toward Marin from Cerralvo. Along the 
way, they picked up some twenty-five survivors of the initial “Ramos 
Massacre.” Arriving in Marin soon after Irvin left, Morgan ordered his 
men to continue south after midnight on the morning of 26 February, 
when a number of Urrea’s lancers attacked them just outside the town. 
When Morgan sent a messenger to Monterrey for reinforcements, his 
courier came upon Irvin’s column marching southward. In response, 
Irvin and 150 of his men turned back to join forces with Morgan, and 
the reinforced column reached Monterrey without further incident. In 
the end, Morgan and Irvin estimated they had killed some fifty partisans 
while suffering five wounded and one killed. Urrea’s force, however, 
effectively closed the route between the Rio Grande and Monterrey. 


Defense of supply convoy (Library of Congress) 



21 






Finally recognizing the seriousness of the guerrilla threat, Taylor 
organized a column of mixed arms under Maj. Luther Giddings to 
run the gauntlet to Camargo. It consisted of about 250 infantrymen, a 
section of field artillery, and approximately 150 wagons. Giddings left 
Monterrey on 5 March and by midafternoon on the 7th had come within 
one mile of Cerralvo, a small town fifty miles southwest of Camargo. 
When local citizens warned him of an impending attack, he quickly 
parked the train and organized his men into a defensive perimeter. 

The initial guerrilla assault failed to break through Giddings’s line 
but succeeded in destroying about forty wagons and killing seventeen 
American civilian teamsters and soldiers. Strengthened by a relief 
column from Camargo the following day, the Giddings column reached 
Camargo without further incident. 

Next, Taylor sent Col. Humphrey Marshall’s 1st Kentucky cavalry 
regiment northward from Monterrey to locate the guerrilla force. 
Marshall soon reported that Urrea was again near Marin. In response, 
Taylor organized a brigade of dragoons, Capt. Braxton Bragg’s battery, 
and Col. Jefferson Davis’s 1st Mississippi Rifles and personally led it 
to Marin. Joining Marshall early on the morning of 16 March 1847, 
Taylor sent a portion of the force to guard a supply train moving out 
of Camargo while the rest of the force pursued Urrea. Although the 
Americans failed to engage the guerrilla leader, their presence in such 
large numbers made further organized partisan operations against 
U.S. supply routes in the region impossible. Subsequently, Urrea 
retired southward toward San Luis Potosi, allowing Taylor to reopen 
his supply lines to the Rio Grande. To prevent similar situations from 
recurring, Taylor continued to send mixed armed groups with each 
convoy. He also positioned additional units at various garrisons along 
his lines of communication and sent “Mustang” Gray’s Texas Rangers 
to operate in the area. The Rangers hoped either to find and eliminate 
the guerrillas or to terrorize the local people to such an extent that 
they would stop supporting the irregulars. Such measures were only 
partially successful. 

On 4 April 1847, General Canales called on all Mexicans to take 
up arms against the Americans and threatened to execute as traitors any 
who refused. Guerrilla attacks increased through the summer and into 
the fall of 1847. A large partisan force raided the supply depot at Mier, 
some 180 miles northwest of Matamoros, on 7 September, carrying 
off some $26,000 worth of supplies. A hastily organized party of 
dragoons and civilian teamsters caught the irregulars, who were slowed 
considerably by their plunder, allowing the Americans to reclaim their 
supplies after killing some fifteen of the enemy. 


22 


By early November 1847, the guerrillas changed their tactics. The 
strong American presence in convoys and at various garrisons made 
attacking those targets less attractive. Instead, the guerrillas focused on 
ambushing small detachments patrolling the countryside. Outside Marin, 
for example, a large force of guerrillas under Marco “Mucho” Martinez 
engaged a detachment of dragoons commanded by 1st Lt. Reuben 
Campbell. This time, the dragoons fought their way through the enemy 
line and killed Martinez, whom Taylor had labeled “the most active of 
the guerrilla chiefs on this line.” 

A few days after Martinez’s death, Texas cavalrymen found and 
raided a guerrilla camp near Ramos, about fifty miles to the north and 
west of Camargo, killing two more irregulars and capturing a large 
number of horses and mules, as well as arms and other equipment. Those 
two victories helped curb the violence that had been common along the 
Rio Grande since the previous May. 

American commanders finally supplemented tactical measures with 
more enlightened policies to reduce violence against civilians. Bvt. 
Maj. Gen. John E. Wool, the military governor of Saltillo, instituted 
strict curfews, moved garrisons out of city centers, set up road blocks 
to keep soldiers away from populated areas, and threatened to discharge 
any unit whose members indiscriminately slaughtered Mexican livestock 
or plundered from the locals. Although conditions improved somewhat, 
violent crimes against Mexican citizens continued. In fact, Taylor himself 
announced that he would hold local governments responsible for U. S. Army 
goods destroyed in their jurisdiction and would lay “heavy contributions 
... upon the inhabitants,” a punitive policy that was effective. 

Taylor and Wool also decided to organize Mexican police forces into 
a lightly armed constabulary that was responsible for particular regions. 
Raised from local citizens, the units were to “ferret out and bring to 
the nearest American military post for punishment ...” any guerrillas or 
their supporters. Although the units’ actions against Comanche Indian 
raiders along the Rio Grande enhanced their local popularity, the units 
had little effect on guerrilla operations. 

Frustrated in September 1847, Taylor granted General Wool the 
authority to try any Mexicans “who commit murder and other grave 
offences on the persons or property ...” of the American Army of 
Occupation. Based on a similar order that General Scott had issued 
in central Mexico, the measure governed military tribunals in the area 
under the general’s jurisdiction and essentially placed the region under 
military law. 

In December, Secretary of War Marcy reinforced the harsh measures 
by directing that local authorities turn guerrillas over to the Americans. 


23 




John E. Wool (National Portrait Gallery, Smithsonian Institution) 

If they failed, then the Army had the authority to hold entire towns 
responsible for any violence that took place in surrounding areas. Any 
Mexicans who provided material support to guerrillas would not only 
pay fines but also forfeit all personal possessions. The measures worked. 
Within a few months, Wool collected more than $8,000 in fines, as well 


24 



as livestock and other personal property. By the end of 1847, attacks in 
northern Mexico had dropped off considerably. 

Wool took command of Taylor’s army on 26 November 1847 when 
the latter returned to the United States. Shortly thereafter, Wool issued a 
scathing proclamation in which he stated that the war had been conducted 
’‘with great forbearance and moderation.” Even so, he said, “Our 
civilians and soldiers have been murdered and their bodies mutilated 
in cold blood.” As a result, anyone who “pays tribute to Canales or to 
any other person in command of bandits, or guerrilla parties ... will be 
punished with utmost severity.” 

Wool’s final report in 1848 credited the decrease in guerrilla attacks 
to three basic policies. First, holding local leaders personally responsible 
for guerrilla activity in their jurisdictions curbed high-level support for 
the irregulars. Second, making localities financially accountable for 
U.S. government property lost in attacks made local citizens hesitant 
to harbor attackers. Finally, Wool contended, the use of native police 
forces helped forge bonds between the Army of Occupation and the 
local populace and allowed the Americans to collect intelligence that 
they would never have found otherwise. Others, however, place more 
emphasis on the large number of troops on security duty, their offensive 
operations against the partisans, and the measures taken to at least 
separate the volunteer troops from the civilian population. 

Scotts Occupation of Central Mexico 

While Taylor struggled with Mexican resistance in the north after 
the battle at Buena Vista, Scott launched his central Mexico campaign 
(Map 3). In February 1847, leading elements of his invasion force 
seized the Gulf port town of Tampico for use as a staging point. Scott’s 
occupation effort began at that point and ended with the American 
withdrawal in July 1848. By then, Scott’s area of control extended 
some 280 miles from the port of Veracruz to Mexico City and straddled 
Mexico’s National Highway—roughly the same route that the Spanish 
conquistadores had followed on their march to the Aztec capital in 1519. 
One of the few paved routes in Mexico, the road allowed heavy wagons 
to move up and down its length with ease. 

From the initial planning stage in October 1846, Scott’s campaign 
had objectives far different from those of Taylor’s northern mission. 
By the time Scott had outlined his plans for the invasion of central 
Mexico, Taylor’s presence in northern Mexico had clearly failed to 
compel the Mexicans to cede California or any of the other territory 
coveted by U.S. leaders. As a result, Scott intended to carry the war to 


25 





the heart of Mexico, capturing the nation’s capital. This, he and the Polk 
administration reasoned, would force Mexico to accept U.S. terms. 

The strategy, although well conceived and necessary to bring the 
war to a successful conclusion, was fraught with danger. Operating in 
Mexico’s most populated territories, Scott’s army would rarely number 
more than 10,000 troops at the leading edge of his advance during the 
entire campaign. For much of the time, Santa Anna’s army outnumbered 
Scott’s by nearly three to one. The Americans would be hard-pressed to 
deal with the Mexican military, let alone any civil uprisings or partisan 
attacks similar to those besetting Taylor. Scott understood from the 
beginning that he would have to secure the loyalty and respect of the 
local citizens or fail in his mission. 


26 























Scott owned an extensive personal library including works on 
the history of Napoleon’s occupation of Spain from 1808 to 1814. In 
particular, Sir William Francis Patrick Napier’s three-volume History of 
the Peninsular War guided his planning for his future campaign. Mining 
French experience for insights, he was struck by the rancorous conduct 
of the French troops toward the Spanish population and the failure of 
harsh French occupational measures to quash the growing uprising there. 
As provocations multiplied on both sides, the fighting escalated out of 
control. The French responded by setting fire to entire villages, shooting 
civilians en masse , destroying churches, and even executing priests. 
The locals retaliated in kind. Although the Spanish irregulars operated 
without any centralized command and control structure, individual 


27 
















bands of guerrillas managed to isolate various French commands and 
wreaked havoc on their lines of communications. By the time an allied 
force under Arthur Wellesley, the Duke of Wellington, compelled the 
French to withdraw from Spain in 1813, Napoleon’s force had seen 
some 300,000 men killed and wounded, compared with Napoleon’s 
preoccupation estimate of approximately 12,000 casualties. In fact, Scott 
saw Wellesley’s stress on strict discipline—insisting his soldiers respect 
personal property and meet the basic needs of Spanish civilians—as the 
proper model for operating in a potentially hostile land. 

In light of his studies, Scott wrote his General Order No. 20, 
commonly known as the Martial Law Order, even before he left for 
Mexico. Issued at Tampico on 19 February 1847, it made rape, murder, 
assault, robbery, desecration of churches, disruption of religious services, 
and destruction of private property court-martial offenses not only for all 
Mexicans and all U.S. Army soldiers but also for all American civilians 
in Mexico. Scott closed the gap by making everyone—whether soldier, 
civilian, or Mexican citizen—subject to the U.S. Army’s jurisprudence. 
All accused offenders would be tried before a court made up of officers 
appointed by the commanding general. 

Scott administered his tribunals, or commissions, in much the same 
way as modern courts-martial. He appointed one Regular Army officer 
to preside over the proceedings as judge advocate of the court. Nine 
other officers, usually from volunteer regiments, made up the jury. 
Another officer prosecuted the case, while an officer from the accused’s 
unit served as a defender. A Regular officer defended civilians, both 
American and Mexican. Commissions heard one case or multiple cases 
over an extended period, sometimes lasting for weeks. The tribunals had 
the authority to determine innocence or guilt and to levy punishment, 
which included the lash, hard labor in ball and chain, imprisonment, 
branding, and even death. The commanding general—and sometimes 
the War Department—had to approve the most severe sentences. 

The system was hardly foolproof. In one notorious case, a volunteer 
from the 1st Pennsylvania Regiment stood trial for theft. The accused 
solider had used the stolen goods, including a watch and a gold crucifix, 
to ensure that his compatriots would support his alibi. He had also bribed 
the defending officer to prevent him from exposing the deception. In the 
end, the soldier went free. 

Scott’s order closed an obvious loophole that had existed in the 
1806 Articles of War, which had previously prescribed the conduct of 
U.S. soldiers in wartime. Because the authors of that code had never 
imagined that the United States would fight a war in foreign territory, 
they failed to extend its jurisdiction beyond America’s borders or to 


28 








make provisions for crimes against civilians. The shortcoming had, for 
all practical purposes, given American volunteers and civilians such as 
teamsters and camp followers immunity from punishment under the 
Articles. Under the 1806 Articles, they would be put on trial either in 
local Mexican civil courts or in civilian courts in the United States. 
Even the Regulars were exempt from the Articles while in foreign 
territory, although they were still held to the U.S. Army’s own strict 
code of conduct. 

In reality, Scott aimed General Order No. 20 at the volunteers. 
Alarmed, both Secretary of War Marcy and Attorney General Nathan 
Clifford argued against its harsh provisions, fearing that the volunteers 
and their families might be enraged and turn to Congress for relief. In 
the end, however, neither man forbade issuance of the proclamation. 

As for the Regulars, both Scott andTaylor held them to strict standards 
throughout the war. Even petty theft was punishable by thirty lashes 
with rawhide. Indeed, many Regulars noted the injustice of volunteers 
literally getting away with murder while they faced extremely harsh 
punishments for comparatively minor crimes. This inequity contributed 
to some of the tension and animosity that existed between volunteer and 
Regular soldiers. 

General Scott’s policies underwent their first test immediately after 
the surrender of Veracruz on 27 March 1847. At that time, Scott reissued 
General Order 20, declared martial law, and arranged for the centralized 
distribution of food to the city’s population, which had suffered serious 
privation during the siege. Another public proclamation stated that the 
U.S. Army was a friend to the Mexican people and that it would do 
away with the abuses that the Mexican government had inflicted on its 
people. 

From this enlightened beginning, Scott’s occupation campaign 
differed markedly from Taylor’s. By insisting on strict discipline, Scott 
preempted many of Taylor’s problems with volunteers. When a military 
commission found two soldiers guilty of stealing from a local store, 
for example, the Army imprisoned both in the town’s dungeon. When 
another commission found Isaac Kirk, a “free man of color” working 
for the Army, guilty of rape and theft, the Army hanged him. Scott 
quickly issued a proclamation on 11 April 1847 declaring that the 
capital punishment proved the Army would protect the Mexican people. 
Those examples and others like them had their effect. Scott reported a 
few weeks later that after the imposition of these sentences, “... such 
offenses by American soldiers abated in central Mexico.” 

Scott also assured merchants that the Army would protect their 
goods. As a result, local markets reopened for business quickly. In 


29 


addition, the general saw to the organization of indigenous work crews 
to clear the streets of debris and accumulated garbage. The citizens not 
only aided in removing visible signs of the war left from the siege but 
also were paid a high salary, which was meant to improve the local 
economy by infusing it with money. The program garnered considerable 
popular support for the occupation. 

Scott repeatedly made the case to civic leaders and to the general 
population that if the Mexican people cooperated with his forces, the 
war would end more quickly and with less devastation. Such policies 
convinced Veracruz’s inhabitants to accept American occupation with 
little noticeable resistance. Life returned to normal in the town, and 
Scott wrote Secretary of War Marcy that the people “are beginning to 
be assured of protection, and to be cheerful.” 

Unlike the Polk administration, Scott understood and honored 
local mores. When Marcy suggested that he raze San Juan de Ulua, the 
culturally important castle in Veracruz, for example, Scott refused on 
grounds that the destruction of such an important site would only sow 
anger and resentment. Scott knew that successful guerrilla campaigns, 
like those in Spain against the French, required an environment hostile 
to the occupiers. He used discipline, good public relations, and an 
understanding of the local culture to keep that from happening. 

To win the war in the shortest possible time, Scott planned to abandon 
many of his resources and to march boldly into Mexico’s interior to seize 
the country’s capital in a single daring stroke. He also understood that he 
could accomplish the task with fewer than 10,000 frontline troops only 
if the Mexicans who lived along the Veracruz-Mexico City corridor 
provided goods and food and declined to rise up en masse against his 
forces. Consequently, Scott insisted that his officers pay in full and 
at a premium price all provisions his army gathered from Mexicans. 
He also ordered, “The people, moreover, must be conciliated, soothed, 
or well treated by every officer and man of this army, and by all its 
followers.” Public opinion had to be favorable, or at least neutral, toward 
the Americans. Thus, as in Veracruz, he maintained strict discipline 
throughout the ensuing campaign to Mexico City and insisted on severe 
punishments for transgressors. When a soldier in the 8th Infantry killed 
a Mexican woman at Jalapa, a military tribunal ordered him hanged. 
The military similarly executed two civilian teamsters in the town for 
murdering a local boy. 

Because of his astute observations and careful planning, Scott faced 
a type of guerrilla different from the one that opposed Taylor. Rather 
than facing an angry population such as the one supporting various 
irregular forces in the north, U.S. forces in central Mexico were beset 


30 


by the Light Corps, highly trained and motivated volunteers fighting in 
formal partisan military units with the explicit consent of the Mexican 
government. 

After their official creation on 27 April 1847, Light Corps units 
were operating in the Veracruz-Mexico City corridor by mid-May 1847. 
They soon became such a menace that Maj. Gen. John A. Quitman, a 
leading southern Democrat and a staunch supporter of President Polk, 
required 1,500 men to escort him from Veracruz to his new command 
with Scott’s main force. Raising this force delayed Quitman’s departure 
from the coast for several weeks. 

The number of attacks on Americans climbed steadily during the 
summer and fall of 1847. The first actions focused on small groups 
of soldiers. In one instance on 2 May 1847, guerrillas rode down two 
soldiers, '‘lassoed” them “around their necks and dragged on the ground,” 
and then speared their battered bodies. Scott responded with Capt. 
Samuel Walker’s mounted Texas Rangers, ruthless fighters outfitted with 
Colt six-shot revolvers. Walker’s men engaged the guerrillas outside of 
La Hoya and Las Vigas, two towns about seventy miles northwest of 
Veracruz, killing some fifty Mexican irregulars. 

Travel on the National Highway, nevertheless, became increasingly 
dangerous. In June, Lt. Col. Ethan Allen Hitchcock, Winfield Scott’s 
inspector general and later his chief of intelligence, began using Mexican 
criminals liberated from prisons as couriers to slip through the guerrilla- 
infested corridor to the coast. His first messenger, a convicted highway 
robber named Manuel Dominguez, assured him that other prisoners 
hostile to Santa Anna and the government would eagerly support 
such missions. Believing that such a group could provide valuable 
intelligence services, Hitchcock proposed recruiting a “Spy Company” 
made up entirely of Mexicans. Scott eagerly endorsed the plan, and 
Hitchcock raised a 100-man force under Dominguez’s command that 
included many former prisoners. 

The company gathered information, provided messengers, and 
acted as guides and translators. Some of its most valuable intelligence 
came from its members who infiltrated Mexico City as “market people 
from Chaleo ... selling apples, onions, etc.” From those missions, the 
spies gave Hitchcock detailed reports about the situation in the city 
and its defenses. Scott also instructed them to capture or kill guerrilla 
leaders whenever possible. As a result, the company captured Mexican 
Generals Antonio Gaona and Anastasio Torrejon during operations near 
Puebla. Overall, the Spy Company performed effectively, easily slipping 
undetected through Light Corps positions along the Veracruz-Mexico 
City road. Concerned, Santa Anna himself offered all of the spies a 


31 



Samuel Walker (Library of Congress) 


“pardon for all past crimes” and “a reward adequate to any service they 
may render to the Republic.” 

Scott also had other sources of human intelligence. Records detail 
that his command spent some $26,622—or more than $520,000 in 
2004 dollars—in payments for information-gathering efforts. Of that, 
Hitchcock paid $3,959 directly to the Spy Company as salaries. The rest 


32 





Ethan Allen Hitchcock (Library of Congress) 


went to informants, deserters, Mexican officers, and even one of Santa 
Anna’s servants. 

As the Americans rushed to create an intelligence apparatus, the 
partisans made American supply trains a continual target. A convoy 
under the command of Lt. Col. James S. McIntosh, for example, left 
Veracruz on 4 June 1847 with nearly 700 infantrymen and approximately 


33 



128 wagons. During the next two weeks, the Light Corps attacked it 
on three separate occasions. The first came on 6 June, as it approached 
Cerro Gordo. McIntosh halted the convoy and called for reinforcements 
after losing twenty-five men who were wounded and killed along with 
twenty-four wagons that were destroyed. A relief column under Brig. 
Gen. George Cadwalader with 500 men reached the besieged unit on 
11 June. Reinforced, the Americans started to move forward again only 
to find the Puente Nacional, or National Bridge, occupied by partisans. 
Located some thirty-five miles northwest of Veracruz, the bridge 
spanned a wide valley with imposing terrain on both its sides, creating a 
perfect bottleneck for the convoy. Only after McIntosh and Cadwaladar 
fought a series of fierce actions against Light Corps positions around 
the bridge, losing thirty-two dead and wounded, was the convoy able 
to continue. Pushing on, it next came under assault on 21 and 22 June 
when an estimated 700 men attacked it at La Hoya. Again, Cadwalader 
and McIntosh’s troops eventually battled their way through. The 
Mexican Spy Company later located additional guerrillas preparing to 
ambush the column yet again, but Captain Walker’s Rangers rushed out 
of their garrison at Perote, a nearby town, and managed to disperse the 
irregulars. The column reached Scott’s main force a few days later. 

After the heavy resistance faced by McIntosh, Scott decided 
to use larger and more heavily armed convoys. Brig. Gen. Franklin 
Pierce, a future president of the United States, departed Veracruz in 
early July 1847 with 2,500 troops, 100 wagons, and 700 mules. Some 
1,400 Mexican irregulars met the supply train at the National Bridge, 
however, and forced Pierce to retreat to Veracruz after losing thirty 
men. Reinforced with artillery and additional forces, Pierce eventually 
reached Scott’s force at Puebla without further incident. 

Another column carrying much-needed supplies departed Veracruz 
on 6 August 1847, guarded by some 1,000 men under Maj. Folliott 
T. Lally. Again, the irregulars attacked, and Lally lost 105 men as he 
fought his way through the resistance. The commander at Veracruz 
sent three companies to assist, but enemy action forced even that relief 
column to return to Veracruz after it lost all but one supply wagon in 
yet another fight at the National Bridge. In the end, Lally managed to 
push through the enemy’s positions and to reach Scott’s army a few 
days later. 

The next supply train set out from Veracruz in September 1847. 
Maj. William B. Taliaferro reported that his force faced daily attacks 
and lost several men in each one. Even at night, Light Corps partisans 
harassed the Americans with heavy fire, but, in the end, Taliaferro 
broke through and reached Scott. 


34 


Because the Light Corps specialized in killing stragglers and other 
men separated from their units and in assaulting small detachments on 
foraging orreconnaissancemissions,Americancommanders increasingly 
sought to keep their forces concentrated. On 30 April 1847, warning 
that “stragglers, on marches, will certainly be murdered or captured,” 
Scott’s orders required officers of every company on the march to call 
roll at every halt and when in camp to take the roll at least three times 
a day. While his force rested at Puebla to await reinforcements, Scott 
also made it a punishable offense to enter the town alone. He instructed 
soldiers to travel in groups of six or more, to be armed at all times, and 
to leave camp only if accompanied by a noncommissioned officer. 

Such orders reflected an additional threat. Men from the Light 
Corps continually worked their way into American garrisons at night, 
killing individual soldiers. In the seaport garrison at Villahermosa, 
Commodore Matthew C. Perry, U.S. Navy, explained that “Mexican 
troops infiltrated the town every night to pick off Americans; this was 
the kind of fighting they liked and they were good at it.” Attempts to 
prevent the attacks proved unsuccessful because “dispersing Mexicans” 
seemed “no more effective than chasing hungry deer out of a vegetable 
garden. They always drifted back, to take pot shots at ‘gringos.’” Col. 
Thomas Claiborne, commander of the garrison housed in the fortress 
Perote, reported that “the guerrillas were swarming everywhere under 
vigorous leaders, so that for safety the drawbridge was drawn up every 
night.” 

Scott’s capture of Mexico City on 14 September 1847 did not 
end his woes. While the Mexican regulars fled, average citizens and 
criminals who had been released from prisons as the Americans entered 
the city began using stones, muskets, and whatever other weapons 
were available to oppose the U.S. Army’s advance. The irregular urban 
combat quickly turned vicious. The U.S. Army responded with close- 
range artillery fire against any building that housed guerrillas. Although 
such tactics ended widespread resistance, the partisans instead focused 
their attacks on individual and small groups of soldiers. 

Meanwhile, the Light Corps continued to restrict the flow of 
supplies, mail, money, and reinforcements to Scott. Shortly after 
pacifying Mexico City in mid-September, Scott turned his mind to the 
problem posed by the increasingly bold partisans. First, he enlarged 
the garrison at Puebla to some 2,200 men and constructed four new 
posts along his line of communications at Perote, Puente Nacional, Rio 
Frio, and San Juan. Completed by November, each post contained about 
750 soldiers. Their commanders were required to send strong patrols 
into the countryside to find and engage irregular forces. Finally, Scott 


35 





Scott entering Mexico City (Library of Congress) 


decided that all convoys would travel with at least 1,300-man escorts. 
Thus, by December, he had diverted more than 4,000 soldiers, or nearly 
26 percent of the 24,500 American troops in central Mexico, to secure 
his supply lines. 

Scott also created a special antiguerrilla brigade and placed it under 
the command of Brig. Gen. Joseph Lane, a veteran of the fighting at 
Buena Vista. Lanes combined-arms force of 1,800 men included 
Walkers Rangers, as well as additional mounted units and light 
artillery, stressing mobility to better locate and engage Mexican Light 
Corps units. The brigade patrolled the Mexican National Highway and 
attempted to gather intelligence from the local population, either through 
cooperation or intimidation. Although not numerous enough to secure 
the entire length of the Veracruz-Mexico City corridor, the brigade did 
succeed in carrying the war to the partisans and their supporters. 

Lane s brigade was most successful in an engagement with a large 
Light Corps unit led by Gen. Joaquin Rea on the evening of 18 October 
1847 outside the town of Atlixco. Lane posted his available artillery on 
a hill overlooking the town and initiated a 45-minute cannonade into the 
irregular positions. After the bombardment, he ordered his force into 
Atlixco. The operation destroyed a significant portion of the Light Corps 
force with Mexican casualties totaling 219 wounded and 319 killed. 


36 





Although Rea escaped with some of his men and several artillery pieces, 
his original unit was largely destroyed. Lane reported that he declared 
Atlixco a guerrilla base and that “so much terror has been impressed 
upon them, at thus having the war brought to their own homes, that I am 
inclined to believe they will give us no more trouble.” In the fight, Lane 
used his mobility to find and engage the enemy and his combined-arms 
team to inflict maximum damage on the Light Corps unit. 

Unfortunately, Lane’s unit became most infamous for a brief 
engagement that followed an incident at Huamantla, a few miles from 
the town of Puebla, on 9 October 1847. When Captain Walker of the 
Texas Rangers fell mortally wounded in the skirmish, Lane ordered his 
men to “avenge the death of the gallant Walker.” Lt. William D. Wilkins 
reported that, in response, the troops pillaged liquor stores and quickly 
became drunk. “Old women and young girls were stripped of their 
clothes—and many others suffered still greater outrages.” Lane’s troops 
murdered dozens of Mexicans, raped scores of women, and burned many 
homes. For the only time, Scott’s troops lost all control. Lane escaped 
punishment in part because news that Santa Anna had stepped down as 
commander of the Mexican Army after the engagement at Huamantla 
overshadowed the American rampage. 

In Washington, however, many would have applauded such an 
incident. Angered by the Mexican partisans’ successes, the Polk 
administration ordered Scott to destroy the Light Corps’ “haunts and 
places of rendezvous,” a directive that eventually led the U.S. forces 
into a scorched-earth policy. Although Scott had his doubts about such 
tactics, he realized the necessity of denying the guerrillas sanctuary and 
thus applied “the torch” as historian Justin Smith commented “with 
much liberality, on suspicion, and sometimes on general principles, to 
huts and villages; and in the end a black swath of destruction, leagues 
in width, marked the route” from Veracruz to Mexico City. When such 
extreme measures failed to stop the Light Corps’ attacks, Scott issued 
a forceful proclamation on 12 December 1847, declaring that “No 
quarters will be given to known murderers or robbers whether called 
guerillos or rancheros & whether serving under Mexican commission 
or not. They are equally pests to unguarded Mexicans, foreigners, and 
small parties of Americans, and ought to be exterminated.” 

Once again, such measures failed to diminish the Light Corps’ 
effect on Scott’s line of supply. On 4 January 1848, a force of some 
400 irregulars attacked a supply convoy near Santa Fe, in the state of 
Veracruz, and carried away 250 pack mules and goods. On 5 January, 
the irregulars attacked another convoy at Paso de Ovejas. Col. Dixon 
Miles, the convoy commander, requested reinforcements of at least 400 


37 



infantrymen plus artillery. Eventually, his column ran the gauntlet and 
reached Mexico City. 

Scott’s efforts to secure his rear line of communication enjoyed 
mixed results. In general, his work to calm and pacify the general 
population generally succeeded. Millions of Mexican civilians living in 
the Veracruz-Mexico City corridor went ahead with their lives as usual, 
and there was little of the spontaneous resistance to the U.S. occupation 
that had characterized events in northern Mexico. Nevertheless, the 
successes of the mounted Light Corps partisans cannot be denied and 
had a deleterious effect on the U.S. Army’s freedom of action. 

Scott s Stabilization Campaign 

Scott’s success against the regular Mexican Army had unexpected 
consequences. Its demise eliminated one of the primary elements 
holding Mexican society together. Without fear of reprisal, peasants 
across the country rose up in revolt. Between 1846 and 1848, some 
thirty-five separate outbreaks occurred across Mexico. In each case, the 
rebels targeted wealthy, landed elites and symbols of the nation’s federal 
authority. A large revolt on the Yucatan peninsula in early 1848 pitted 
some 30,000 Indians against wealthy white landowners and merchants 
living in the region. The governor of the state issued an urgent plea 
for help, saying that the peasants were waging a “war of extermination 
against the white race.” Here and elsewhere, the unrest took a high toll 
in both human and economic terms. 

The state of unrest caused the U.S. Army two problems. First, the 
revolts steadily grew in size, frequency, and violence, thereby threatening 
to engulf U.S. forces. If the peasant revolts that swept through Veracruz 
targeted Scott’s army, as well as the upper-class Mexicans, all could be 
lost. Second, without a strong central government in place, no peace 
treaty with Mexico would be possible and thus no legal guarantee for 
the territorial acquisition that the United States desired. As President 
Polk explained about Mexico, “Both politically and commercially, we 
have the deepest interest in her [Mexico’s] regeneration and prosperity. 
Indeed, it is impossible that, with any just regard to our own safety, we 
can ever become indifferent to her fate.” 

The Mexican elites recognized the necessity of reaching some sort 
of peace accord before they could rebuild their army, the prerequisite 
ensuring their hold on power. The central government, in exile since 
Scott occupied the capital, thus faced a conundrum. It confronted 
a two-front war, one with the United States and the other with the 
rebellion, the former gradually appearing as the lesser of two evils. The 


38 


northern aggressor desired territory, while the ruling elite feared that 
the Mexican people wanted nothing less than a race war that would lead 
to the destruction of the elite or elimination of its power and privilege. 
In the end, although the rebellion caused the Americans concern, it and 
some twenty-two months of warfare and occupation persuaded Mexico’s 
political leaders to end their resistance and to pursue peace. 

As a result, the two sides agreed to terms on 2 February 1848 in 
the Treaty of Guadalupe Hidalgo. Although it took several months for 
both governments to ratify, the accord met most American demands. 
Mexico recognized U.S. sovereignty in Texas, with its southern border 
resting on the Rio Grande, and agreed to cede Upper California and 
New Mexico, the region that eventually became the states of Arizona, 
California, Nevada, New Mexico, and Utah, as well as portions of 
Colorado, Nebraska, Oklahoma, and Wyoming. In return, the United 
States promised to pay Mexico $15 million in gold and to assume 
responsibility for all outstanding claims that American citizens had 
against Mexico. In short, the war with Mexico and the Treaty of 
Guadalupe Hidalgo largely defined the current western borders of the 
United States, making a country that stretched from coast to coast. 

While the two nations carried out their respective ratification 
processes, they concluded a truce on 6 March 1848. This often- 
overlooked document not only confirmed that all hostilities had 
ceased but also included a stabilization plan to rebuild the Mexican 
government. One important part of the agreement read, “If any body of 
armed men be assembled in any part of the Mexican Republic with a 
view of committing hostilities not authorized by either government, it 
shall be the duty of either or both of the contracting parties to oppose 
and disperse such body; without considering those who compose it.” 
In effect, the United States promised to support the existing Mexican 
government against any internal rebellions, while Mexico agreed to 
disband any guerrillas still operating against U.S. forces. 

The measure benefited the American Army more than the Mexican 
government, as Light Corps units raised and directed by the federal 
government almost immediately ceased troubling Scott’s forces. The 
agreement accomplished what the American military could not do by 
force of arms alone—end guerrilla attacks in the Veracruz-Mexico 
City corridor. Elsewhere, Mexican rebels of all stripes simply avoided 
the U.S. military and concentrated their efforts in areas outside of U.S. 
control. 

The stabilization plan also provided that the United States would 
supply modern weapons to the Mexican government to aid in the 
reconstitution of the federal army. In the first delivery alone, the Mexicans 


39 



received 5,125 muskets, 762,400 cartridges, 208 carbines, and 30,000 
carbine cartridges from local American supply depots. The U.S. Army 
sold the munitions at a greatly reduced price, less than half of their 
market value. More important than the sheer numbers was the quality 
of the equipment. The American weapons were of the latest pattern and 
much more accurate than those that the Mexican Army had previously 
possessed. At the battle of Palo Alto, for example, a large number of 
the Mexican small arms had been outdated and unserviceable British 
Brown Bess muskets. 

Finally, in an effort to stabilize the Mexican economy, the 
Americans allowed Mexican merchants to join their convoys between 
Veracruz and Mexico City and to sell their wares to the Army. That 
corridor had long served as a key commercial route, and thus the U.S. 
presence expanded trade and provided a great, albeit temporary, boost 
to the region’s economy. The U.S. Army also escorted Mexican traders 
who carried precious metals from the mining regions in northern Mexico 
to the Rio Grande and eventually to the Gulf coast. 

The US. Army and the Problems of Occupation 

Although U.S. forces won every conventional battle, a multitude 
of issues arose to threaten the occupation once it began. Logistical 
difficulties in particular proved a major factor. The simple movement 
of the materiel deep into Mexico over rough roads took significant 
planning. Army Quartermasters partially alleviated their difficulties 
by creating a series of forward supply depots in the southern United 
States along the Gulf coast and up the Rio Grande. Those depots 
permitted the Quartermasters to pre-position equipment and supplies 
and to forward them far more quickly to critical points in the theater 
of operations. However, a general shortage of transport—whether 
steamships to move supplies up the Rio Grande, wagons to traverse 
level areas with established roads, or pack mules to caravan through 
mountainous regions—prevented many goods from reaching the troops 
in a timely manner. As a result, American forces had to acquire much of 
their supplies directly from local Mexican sources, often by purchasing 
them at premium prices. 

As supply lines lengthened, the effort to guard those routes became 
difficult and required increased numbers of troops. Early in the conflict, 
Taylor had paid little attention to convoy security. Because of that, 
Mexican guerrillas scored several impressive victories against lightly 
armed supply trains and managed to carry away tons of supplies, 
money, and mail. In the end, both Taylor and Scott were forced to 


40 




divert a significant number of frontline units to accompany convoys 
and garrison their lines of communication. Rather than adopt a district 
form of organization with command elements in specific regions, both 
Taylor and Scott simply positioned troops at individual posts. Scott 
assigned particular brigades or divisions to patrol specific portions of 
his line of supply or to conduct convoy escort duty. Taylor, as usual far 
more disorganized, committed regiments to garrison and escort duty in 
an ad hoc manner. In both cases, the increased escorts and garrisons 
eventually decreased the amount of materiel lost, but their presence 
never prevented the guerrillas from attacking. 

Individual couriers who moved alone to carry messages and 
important orders to far-flung units often fared worse. Mexican guerrillas 
and bandits consistently targeted them. In one famous incident, 
guerrillas ambushed and killed a messenger carrying a note to Taylor 
detailing the amphibious assault on Veracruz and the shift of American 
military forces to central Mexico. The guerrillas promptly conveyed the 
letter to Santa Anna, who responded immediately by attacking Taylor’s 
reduced army at Buena Vista after which he planned to rapidly turn 
south and defend Veracruz against Scott. Fortunately for the Americans, 
Taylor’s force held the field against Santa Anna at Buena Vista, inflicting 
heavy casualties, although the Mexican general managed to escape and 
organize an army to face Scott during the Mexico City campaign. 

Religion also played a crucial role in the occupation. The concept 
that America had a God-given Manifest Destiny served as a powerful 
justification for the conflict. Yet, the idea itself contained strong anti- 
Catholic views that undisciplined volunteers easily acted out in Mexico, 
sometimes making the Catholic Church and its property their targets. 
Although the enlisted ranks of the Regular Army itself included many 
Catholics, Protestants made up the bulk of the volunteers. In fact, many 
officials in the Polk administration and the Army feared that such conduct 
would lead to an all-out religious war. For example, when volunteers 
stabled their horses inside the Shrine of San Francisco in Monterrey, 
the local population was incensed. Concerned, Polk approached several 
Catholic bishops in the United States, requesting that they attach 
chaplains to the Army in Mexico to allay fears that the Americans 
intended to destroy the Catholic Church. Two priests accompanied 
Taylor’s force through mid-1847, although bandits murdered one and 
the second left because of ill health. 

General Scott reacted differently. Instead of assigning priests to 
his columns, he ordered that the troops respect all Catholic priests and 
church property. When one drunken soldier beat a church worker, a 
military tribunal sentenced him to twelve lashes and hard labor in a ball 


41 


and chain for the duration of the war. The message quickly spread to 
the rank and file, Regular and volunteer alike. Scott himself regularly 
attended Catholic mass whenever possible. To further his image as a 
friend to the Mexican Catholics, Scott took one final step by promising 
that the U.S. Army would protect all church property. In contrast, Santa 
Anna and Mexican President Valentin Gomez Farias attempted to fund 
the resistance effort by confiscating and selling church assets, a practice 
that outraged religious Mexicans. After occupying the capital, Scott 
curried favor with conservative criollos by strictly prohibiting the sale 
of any church property without his consent, allaying many fears that the 
Americans intended the church’s destruction. Although Scott’s conduct 
calmed the Mexicans, many American volunteers, nevertheless, resented 
his favoritism toward the church, a policy that may have damaged his 
postwar popularity at home. 


Analysis 

Two distinct zones of occupation were led by two different 
commanders during the conflict. One was in northern Mexico under 
Zachary Taylor, and the other was in central Mexico and was led by 
Winfield Scott. In both regions, the Army’s occupation policies had 
successes and failures. Many shortcomings could be traced to the use 
of poorly disciplined volunteers serving under bad officers. In addition, 
the Army also discovered that its force structure, although well suited 
to fighting conventional battles, was often inappropriate for conducting 
counterinsurgency missions. 

Taylor’s occupation in northern Mexico began easily enough. 
However, he failed to institute any formal policies to keep his own troops 
or Mexicans who opposed the occupation in check until the last few 
months of the conflict. In the interim, his loose control over everyone in 
his zone of influence led to disorganization and violence, which could 
not be overcome solely by harsh, oppressive measures. Indeed, often 
such responses were counterproductive, fueling continued dissent. 

Scott, however, insisted on strict discipline and a code of conduct 
before his troops ever set foot in Mexico and enforced such procedures 
throughout the campaign. His military tribunals, which held all of his 
troops—whether Regulars or volunteers—to the same code of conduct, 
limited senseless violence against Mexicans and created an environment 
in which the local population felt secure with the American presence. 

Clearly, the behavior of the American volunteers sparked local 
Mexican guerrillas. Both Regulars and volunteers themselves pointed 
to the senseless violence perpetrated by America’s volunteer troops. 


42 




Some were criminals in civilian life who continued their lawless ways in 
Mexico; others, particularly the Texans, had a long history of violence 
in their relations with Mexicans. Many were racist and anti-Catholic, 
reflecting the society from which they were drawn, and almost all were 
simply overcome with the unfamiliar rigors of military life and the 
boredom of garrison duty. Their collective actions played a significant 
role in creating guerrilla fighters and an atmosphere that encouraged 
the average Mexican to support the irregulars, especially in northern 
Mexico. 

Because of the differences between Taylor and Scott in their 
occupation policies, the Mexican guerrillas in the two regions 
differed in many ways. In northern Mexico, highway robbers, bandits, 
and persons bent on revenge perpetrated many of the assaults on 
individual and small groups of American soldiers. Taylor’s inability or 
unwillingness to control his volunteers fueled those types of attacks. 
Not until relatively late in the occupation did he and Wool rein in their 
unruly troops. Belatedly, they created tribunals to try both soldiers and 
Mexican citizens and took steps to impose various punitive measures 
aimed at destroying popular support for guerrilla fighters. 

During the Buena Vista campaign, the Americans in northern 
Mexico also faced structured and organized partisans. Those irregulars 
focused their attacks on supply trains and small garrisons. Initially, 
Taylor did little to make convoy security a priority, but after guerrillas 
closed the Camargo-Monterrey supply corridor, he began to divert 
more and more of his frontline troops to guard duty. Eventually, the 
presence of so many American troops guarding the supply lines made 
it too dangerous for large groups of guerrillas to operate in the region. 
The mission, however, limited the ability of Taylor’s forces to pursue 
any further offensive operations. 

Scott’s case differed. Individual guerrillas certainly took the 
opportunity to prey on lone American soldiers in central Mexico, but 
the general’s close control of his volunteers allayed many problems 
in the region. For the most part, his forces faced highly organized 
partisans fighting under the commanders of various Light Corps units. 
The semiconventional forces focused on disrupting Scott’s lines of 
communication. Responding quickly, Scott provided escorts for all 
American wagons moving along the Veracruz-Mexico City corridor, 
organized special brigades to hunt down irregulars, created a series 
of garrisons at key points along the Mexican National Highway, and 
endorsed the creation of the Mexican Spy Company. Again, the drain on 
the Army’s troop resources was considerable. Even with those measures, 
however, he found it impossible to stop all the attacks. 


43 


The Americans found that their force structure, while well adapted 
to winning the conventional war in Mexico, fell short of meeting the 
demands of the irregular conflict that raged in occupied areas of the 
country. Specifically, the lack of mounted units prevented American 
commanders from actively seeking out and engaging guerrillas. Lack 
of mobility forced the U.S. Army to take a defensive role and to react to 
irregular attacks whenever they occurred. Even then, lack of mobility 
prevented its troops from responding in time. American columns had 
to remain on the roads, unable to decisively engage the fast-moving 
guerrillas, who blended with the local population. Time and again, large 
American forces arrived too late to catch the elusive, mounted guerrillas. 
Even the few mounted U.S. Army regiments available enjoyed only 
sporadic success. Out of frustration, some soldiers in those units often 
attacked innocent Mexicans. 

Mexican responses to the occupation varied in effectiveness. In 
the north, individual guerrillas often carried out attacks to avenge 
American atrocities without any sense of planning or strategic purpose. 
Although the attacks created a bloody war of retribution in areas where 
they occurred, they did little to challenge American authority. When 
Generals Taylor and Wool brought their troops under discipline and 
provided the Mexicans with a sense of security, the violence diminished 
and the number of attacks decreased significantly. The northern 
resistance did score a significant success, however, when it used large 
groups of partisans fighting under trained military leaders during the 
battle of Buena Vista. Those organized forces cut Taylor’s access to his 
vital supply line on the Rio Grande. Not until the Americans committed 
thousands of troops to the Camargo-Monterrey corridor were they able 
to compel the Mexicans to retreat. 

In the south, Light Corps units proved extremely successful in 
disrupting Scott’s otherwise nearly flawless thrust toward Mexico City. 
The officially sanctioned, well-led, and well-trained forces endangered 
all American attempts to move along the National Highway and scored 
a number of limited victories. Even as Scott devoted more attention and 
troops to defeating the Light Corps, his lack of cavalry and his inability 
to force the irregulars into a decisive engagement frustrated his plan. 
Yet, even with all of their successes, the Light Corps did not alter the 
outcome of the war. 

Lessons learned in the occupation of Mexico also had long-lasting 
effects on America’s military establishment. It most certainly provided 
valuable experience for junior U.S. Army officers and enlisted men— 
experience they would find invaluable thirteen years later when the 
American Civil War began. For example, young officers such as Ulysses 


44 



S. Grant came to realize how crucial a robust intelligence collection 
network was to Scott’s success in the Mexico City campaign. Grant 
used this lesson to good effect throughout the Civil War, particularly 
during the Vicksburg campaign. In addition, Scott’s General Order No. 
20 has influenced generations of military thinkers. In the American 
Civil War, War Department General Order No. 100, dated 24 April 

1863, was based in large part on Scott’s order. That document, in turn, 
would provide the basic framework for the first Geneva Convention in 

1864, as well as later conventions. 

Although the numbers of killed and wounded in the major battles 
are relatively certain, it is much more difficult to calculate absolute 
numbers of men serving, or who died of other causes, because record¬ 
keeping in the mid-1800s was imprecise at best. The statistics in the 
1846-47 reports by the Secretary of War, however, make it possible 
to approximate the figures. During the conflict, 78,718 American 
servicemen served in the theater. From the start of the conflict through 
January 1848, 1,556 soldiers were killed and another 4,152 were 
wounded during the conflict’s major battles. Also, from January 1848 
until the final withdrawal of American personnel, the Army also lost 
approximately 4,500 additional men from a variety of causes, including 
combat, disease, and desertions. The available statistics cannot account 
for the fate of some 2,800 men. This evidence strongly suggests that 
guerrillas and other irregular forces were responsible for many of those 
losses. Any concrete proof, however, will be impossible to locate. 
Extant primary sources written by American officers tend to minimize 
or even completely ignore irregular forces. Estimating the number 
of civilians, primarily wagon teamsters, killed during the conflict is 
completely outside the realm of possibility because no agency kept track 
of their presence. But we do know that guerrillas killed large numbers 
of civilians during specific time periods. In late February 1847 alone, 
partisans operating on the Carmargo-Monterrey corridor killed some 
65 civilian teamsters. In the end, though, disease and accidental death 
proved far more deadly, killing approximately 11,550 troops. 

Neither American victories in the field, nor Taylor’s mismanaged 
efforts in the north, nor Scott’s well-organized occupation in the heart 
of the country was the lone compelling reason that Mexico made peace. 
Internal Mexican political and social discontent and fear of widespread 
peasant uprisings helped convince members of the nation’s political 
elite that further resistance threatened their survival. A combination 
of twenty-two months of conflict, occupation, and civil strife finally 
allowed the Polk administration to achieve all of its war aims. 


45 


Further Readings 


-. Bauer, K. Jack. The Mexican War, 1846-1848. New York: 

Macmillan, 1974. 

-. Foos, Paul. A Short, Offhand, Killing Affair: Soldiers and 

Social Conflict During the Mexican-American War Chapel Hill, 
NC: University of North Carolina Press, 2002. 

-. Levinson, Irving. Wars within Wars: Mexican Guerrillas, 

Domestic Elites, and the United States of America, 1846-1848. Fort 
Worth, TX: Texas Christian University Press, 2005. 

-. Smith, Justin H. The War with Mexico. New York: Macmillan, 

1919. 

-. Winders, Richard B. Mr. Polks Army: The American Military 

Experience in the Mexican War. College Station, TX: Texas A&M 
University Press, 1997. 


46 







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